Several studies investigated environmental and dietary risk factors for gastric cancer and precancerous gastric lesions in Shandong Province, a high-risk area for gastric cancer in China. A study of 3,400 subjects selected at random with precancerous gastric lesions in Shandong, China revealed that the prevalence of intestinal metaplasia (IM) was 52.8% and that of dysplasia (DYS) 20.1% in this population. The incidence of DYS was greater in subjects with IM of the colonic intestinal type than the small intestinal type (p<0.01). A cohort study among this population demonstrated a significantly elevated risk of gastric cancer for subjects with baseline superficial IM (Odds Ratio (OR)=17.1), deep IM or mild DYS (OR=29.3) and moderate or severe DYS (OR=104.2), as compared with subjects with chronic atrophic gastritis (CAG) at baseline. Helicobacter pylori (H. pylori) infection at baseline was a risk factor for progression to DYS/GC after a 4.5-year follow-up. The risks of the progression to DYS/GC increased with the number of years of smoking cigarettes and with number of cigarettes smoked. In contrast, risks of progression to DYS/GC decreased by 70% (OR=0.3, 95% CI, 0.1- 0.7) among persons with 1989-1990 serum ascorbic acid levels in the highest tertile, as compared with those with lower levels. An endoscopic survey conducted among 214 adults aged 35-64 in Cangshan County, a low-risk area for gastric cancer in Shandong, confirmed the low prevalence of precancerous gastric lesions there and suggested that gastric lesions were strongly associated with H. pylori infection. The OR of CAG associated with H. pylori positivity was 4.2, while the OR of IM/DYS associated with H. pylori positivity was 31.5. Interestingly, this region is known for its production of garlic, which the inhabitants consume at a rate of 20 grams of garlic per day on average. The consumption of garlic showed non-significant protective effects and an inverse association with H. pylori infection. A study of H. pylori infection and mode of transmission among 98 children aged 3-12 years and 289 adults aged 35-64 in Linqu County showed that the prevalence of H. pylori infection clustered within families with at least one infected parent (OR=30.4).Data collection is proceeding on a large study of biliary tract cancer in Shanghai. By the end of 1999, biological specimens and questionnaire data will be obtained from 600 cases, 600 population controls, and 600 surgical controls. A new bacteriology protocol was implemented to detect H. pylori in bile specimens. Human Subjects & Human Subjects: Interview, Questionaires, or Surveys Only & Human Tissues, Fluids, Cells,etc.